An example of the conventional apparatus of this sort is shown in FIG. 1, in which indicated at (1) is a treating pool, at (2) water to be examined, at (3) a water examining instrument, and at (4) a base of an elevator mechanism for lifting up and down the water examining instrument (3) and having an upright support column (5) securely erected thereon. An elevator frame (7) which is linked to an elevating handle (6) through a lift mechanism, not shown, is movable up and down along the support column (5) by rotation of the elevating handle (6). Denoted at (8) is an arm which is securely fixed to the lift frame (7) at one end thereof and provided with a bracket (9) at the other end for supporting the water examining instrument (3) therein. The reference numeral (10) indicates a guard rail which is provided for the sake of safety in most cases.
With the conventional elevator mechanism of the above described construction, the elevator frame (7) is lifted up and down by turning the elevating handle (6), moving up and down therewith the water examining instrument (3) by the lift arm (8) and bracket (9) which are securely fixed to the elevator frame (7).
When the level of water to be examined is low, however, it becomes necessary to employ a long water examining instrument which needs to be lifted up and down over a greater distance by the use of a large elevator mechanism with a greater lift, resulting in a costly, instably tall elevator construction. Besides, the maintenance and service of the detector or other parts of the water examining instrument involves considerable labor and dangerous operations, requiring the operator to lean out over the pool or to move the elevator as a whole.